Effect of Prophylactic Administration of Hyperimmune Plasma to Prevent Rhodococcus equi Infection on Foals from Endemically Affected Farms

Abstract

The effect on foals of prophylactic administration of hyperimmune plasma to prevent R. equi infection was investigated on three farms at which R. equi infection was endemic. Sixteen foals between 10 and 39 days of age were intravenously given 1-2 l of hyperimmune plasma. ELISA antibody titres against R. equi were significantly increased and maintained at high levels for over 30 days in most of the recipient foals. The prevalence of R. equi infection was 6.3 % (1/16) in the foals that received the immune plasma, and 26.3 % (5/19) in the control foals not given the immune plasma on the three farms. For 2 years before and after this field trial on the three farms, 18 of 64 foals (28.1 %) showed clinical signs of respiratory tract infection and four of them died of R. equi pneumonia. Heavy contamination of horses and their environment with virulent R. equi was detected by colony blotting, and plasmid profiles also suggested that foals on the three farms were constantly exposed to virulent R. equi. The results of this field trial support previous observations by some researchers that the administration of hyperimmune plasma to foals in the early days of life promotes prevention of R. equi infection on endemic farms; however, the mechanism of hyperimmune plasma protection remains unclear. U. S.

Rhodococcus equihyperimmune plasma decreases pneumonia severity after a randomised experimental challenge of neonatal foals

“…Moreover, the efficacy of treatment is typically based on year-to-year comparisons (Becu and others 1997). Another confounder is the age of the foal at the time of administration of HIP (Madigan and others 1991, Higuchi and others 1999, Perkins and others 2002). Thus, early administration of HIP is critical (Chaffin and others 1991) as foals are most susceptible to infection within the first few weeks of life (Horowitz and others 2001, Chaffin and others 2008, Dawson and others 2010, Sanz and others 2013).…”

Chemoprophylactic effects of azithromycin against Rhodococcus equi–induced pneumonia among foals at equine breeding farms with endemic infections

“…13 Although this is the best prophylactic program available, it is cost prohibitive for many horse owners, labor-intensive, and not universally effective. [13][14][15][16][17][18][19] A novel strategy for prevention of pneumonia caused by R equi is the administration of effective antimicrobial agents to high-risk foals during the critical period when they are most likely to become infected with R equi. This strategy requires an antimicrobial that is safe, achieves therapeutic concentrations within tissues and cells at the primary site of infection, and maintains adequate concentrations throughout the critical period for infection.…”

Prophylaxis of Rhodococcus equi pneumonia in foals – a review of literature

“…Auch der Einsatz von Hyperimmunplasma (HIP) zur Prophylaxe der R. equi-Pneumonie ist gemäß einiger Studien erfolg-reich (Martens et al 1989, Madigan et al 1991, Becú et al 1997, Higuchi et al 1999, aber auch laut anderer Autoren und jüngerer Studien nicht effektiv (Chaffin et al 1991, Hurley und Begg 1995, Giguère et al 2002, Perkins et al 2002, Caston et al 2006. Trotzdem gilt das HIP bis heute als einziges Mittel, das sowohl unter Feld-als auch unter experimentellen Bedingungen in der Lage ist, die Morbidität zu senken, vorausgesetzt die Verabreichung erfolgt vor der Exposition mit R. equi (Martens et al 1989).…”

“…Ähnlich wie beim spezifischen Hyperimmunplasma zeigte sich, dass die Anzahl an Fohlen mit Lungenabszessen in der Plasma-Gruppe und in der unbehandelten Kontrollgruppe identisch waren (Perkins et al 2002), allerdings erkrankten die Fohlen durchschnittlich 3 Wochen später (Schulte 2005). Für diesen positiven Effekt wurden unspezifische Immunfaktoren wie Fibronektin, Komplementfaktoren, Cytokine und die opsonierenden Eigenschaften von Plasma und HIP verantwortlich gemacht (Madigan et al 1991, Hurley und Begg 1995, Higuchi et al 1999, Hooper-McGrevy et al 2001, Giguère et al 2002, Perkins et al 2002.…”